题目如图,PAPAPA,PBPBPB是⊙O\odot O⊙O的切线,切点分别为AAA,BBB.若∠OBA=30∘\angle OBA=30^{\circ}∠OBA=30∘,PA=3PA=3PA=3,则ABABAB的长为______.知识点:切线长定理章节:图形的性质 / 圆